1. Field of the Invention
The present invention relates to a settling judgment method for judging whether an object is settled in a target position or is following up the target position in a positioning control device for moving an object to a target position by an actuator, and its position control device and more particularly to a settling judgment method for a positioning control device for accurately judging settling even if vibration is applied, and a positioning control device.
2. Description of the Related Art
A positioning control device for moving an object to a target position is widely used. For this positioning control device, especially used for a disk device, for example, high precision positioning is demanded. Particularly for a magnetic disk device and optical disk device, accurate positioning of the head to the target track is extremely important to improve recording density. Settling judgment is a method for judging whether positioning to the target position is being controlled accurately.
In the settling judgment of a positioning control device, the positioning control after moving or after the position deviates must satisfy predetermined positioning conditions for a predetermined time. For example, in the case of the magnetic disk device, settling judgment after seek control and settling judgment during follow up control are used.
In this settling judgment, it is judged as settling completion when the value of a judgment formula based on a position error is continuously in a predetermined slice range, and the number of times of continuation is more than a predetermined count (sample count). For example, a method of judging settling completion when the position error itself is within a predetermined slice range continuously for a predetermined count, and a method of judging settling completion when the position error itself and a difference between position error of a previous sample and position error of a current sample (estimated position of one sample ahead), are within a predetermined slice range continuously for a predetermined count.
As a settling judgment method, a method for estimating the position of the next sample (Japanese Patent Application Laid-Open No. H08-106742) and a method for using an estimated position using an observer have been proposed (Japanese Patent Application Laid-Open No. H04-298868).